With the development of digital technology in recent years, various electronic devices capable of communicating and processing personal information while being in motion, such as a mobile communication terminal, a personal digital assistant (PDA), an electric scheduler, a smart phone, and/or a tablet personal computer (PC) have been released. Since the purpose of such an electronic device is portability, a battery, e.g., a removable battery, is used as a power supply means. A battery may output a voltage and a current proper for each electronic device.
An electronic device supports a battery or supports the form of an auxiliary battery. The electronic device may not individually monitor the quantity of electric charge of the auxiliary battery and a battery state. For example, when multiple batteries are connected to the electronic device, each state of the multiple batteries may not be monitored or managed. In addition, since the multiple batteries are connected to the electronic device in a parallel structure, the full charging capacity of the electronic device may be expanded, but each battery may not be selectively used or charged. Therefore, a transfer of electric charges among multiple batteries according to a selection by a user is impossible. Further, when a main battery that is connected in a circuit to a main power of the electronic device is disconnected from the electronic device, the power of the electronic device may be turned off. Therefore, the main battery may not be changed while the electronic device is being used.